When cloning a field in aui form builder, it excludes the values of all hidden attributes.
For example if you if have this configuration for textarea field.
iconClass: 'form-builder-field-icon form-builder-field-icon-textarea',
label: 'Custom Label',
By clicking the clone button, the text area will be cloned, but it will have an empty string for it's label. The cloned field should respect that it's hidden, but still clone the value.